Evangelist and author Anne Graham Lotz has urged Americans to come together in prayer, warning that the nation is "seriously divided" in a "toxic, dark, dangerous" world.

"The atmosphere in our world is explosive. Toxic. Dark. Dangerous to the extreme. And at this very moment when our nation should be standing together against wickedness and lawlessness, we are seriously divided," Lotz wrote on Facebook on Thursday.

"It's time to 'inquire of the Lord.' Now! It's time to humble ourselves and pray and seek God's face and turn from our wicked ways, so He will hear from heaven and forgive our sin and heal our land. (2 Chronicles 7:14)," she added.

Lotz linked to a page on her website providing people with a space to come and post their prayers.

"My purpose is to encourage you and myself to remain faithful, focused, and fired-up in prayer during these dangerous, dark, and divided days. Then remain attentive to what God may say to us in reply," she said.

Her comments come days after her brother, evangelist Franklin Graham, prayed at President Donald Trump's rally in Arizona on Tuesday, saying that the nation's sins have "paralyzed" it.

"We come tonight as a troubled nation. We are broken spiritually. We are divided politically. We are divided racially. And we are adrift morally, following the whatever direction the wind of popular culture blows with no regard for Your Word or the consequences of our disobedience. We ask tonight for your help."

In May during the National Day of Prayer observance at the U.S. Capitol, Lotz listed 12 "national sins" that she said are afflicting the country.

"I believe we are going through a time in our nation that I would describe a spiritual drought," Lotz said, noting that the only solution is to come before God and repent.

"If this is so and if the problems in our nation are coming because God is missing, then issuing an executive order will not fix that, and politics will not fix that, and immigration reform, and health reform, and some of these other things will not fix that.

Ronnie Floyd, former Southern Baptist Convention president and pastor of Cross Church in Northwestern Arkansas, said at the same event that racism and abortion are also two big sins in America.

"Lord, when we look across our country, we think about things that still breaks our heart. And forgive us of the deplorable, the wicked sin of killing the unborn and justifying it and rationalizing it," Floyd prayed at the time.

"We pray tonight against the injustice toward people, against the wicked sin of racism, that is completely opposite of the Gospel of Jesus Christ."

Lotz, who is also the daughter of world renowned evangelist Billy Graham and founder of AnGeL Ministries, warned earlier in August that Monday's solar eclipse in the U.S. could be a sign from God.

"While no one can know for sure if judgment is coming on America, it does seem that God is signaling us about something. Time will tell what that something is," the evangelist said.